Process of manufacturing built-up permanent magnets



Jan. 8, 19 46. 115m 2,392,592

PROCESS OF MANUFACTURING BUILT-UP PERMANENT MAGNETS Filed Dec. 12, 1940Patented Jan. 8, 1946 PROCESS OF MANUFACTURING BUILT-UP PERMANENTMAGNETS Takeshi Iseki, Toyonaka, Japan; vested in the Alien PropertyCustodian Application December 12, 1940, Serial No. 369,882

In Japan December 29, 1939 2 Claims.

, This invention relates to improvements in the process of manufacturinga built-uppermanent ma net which consists of a piece of magnet and twopieces of soft iron attached to said magnet with one end of each softiron piece acting as the magnetic pole, and more particularly to themethod of building up a permanent magnet, wherein a magnet piece and twosoft iron pieces are put together by an intervention of thin nonmagneticmetallic plates which are attached to both sides of the magnet and softiron pieces by electrical spot-welding method, and the tight and closecontact of the magnet and soft iron pieces is made by the contraction ofthe heat-expanded metallic plates.

Hitherto, the elements of the built-up permanent magnet has been puttogether by means of screws, solder or riveting, but these methodsinvolve such diiilculties as drilling and tapping in the soft iron andnon-magnetic metallic plates leaving unavoidable and allowable clearancebetween the contacting surfaces of the magnet and soft iron pieces,thereby causing a considerable magnetic loss. Moreover, these processesare expensive and clumsy because it is not an easy task to get a properfit of the magnet into the space formed bythe soft iron pieces and thecovering metallic p tes.

The present invention successfully does away with these difficulties.and perfect contact between the magnet and soft iron pieces can bereadily and economically attained.

Fig. l is a side elevation showing one form of a built-up permanentmagnet according to the present invention;

Fi 2 is a sectional view taken on the line 11-11 of Fig. 1;

F18. 3 is a side elevation of another form of the invention showing inaddition, means for holdin the parts of the magnet in position forpermanent attachment to one another, and

Fig. 4 is a sectional view, partly in elevation, taken on the line IV-IVof Fig. 3.

As shown in Figs. 1 and 2 a built-up permanent magnet made according tothe present invention, wherein two soft iron pieces B with one end ofeach as the pole are put together with the permanent magnet piece A byan intervention of two pieces of thin non-magnetic metallic plates Cplaced so as to cover both sides of the ma net and the soft iron pieces.

To build up the permanent magnet according to this invention, the magnetpiece A and the soft iron pieces'B are tightly put together in facialcontact, and non-magnetic metallic plates C are placed on both sides ofthe magnet and the soft iron pieces so as to bridge them over. Then thenon-magnetic plates alone are heated for a few seconds, and theprearranged elements are electrically spot-welded at the pointsindicated in the drawing by small dotted circles D. When thenon-magnetic metallic plates are cooled, the magnet and the soft ironpieces come to very tight and close contact with eachv other due to thecontraction of the metallic plates. It is necessary that the contactingsurfaces of the magnet and the soft iron pieces previously be finallyfinished to insure close contact. I

In the example of Figs. 3 and 4 soft iron pieces B are placed on bothends of the permanent magnet A so that the permanent magnet is heldbetween the soft iron pieces.

E is a frame of the device made of a metallic circular ring. G are setscrews radially provided on the frame of the device the inner ends ofthe screws being extended into the inside of the frame.

A spring arm H is pivoted on each surface of the frame. This spring armcan be swung by means of a knob I, and when it is swung outwardly itsfree end rides on the surface of the frame.

To practise this invention, the elements, that is, permanent magnet A,soft iron pieces B and covering plates C are inserted in the frame ofthe device as illustrated in the Figures 3 and 4, and the permanentmagnet and the soft iron pieces are put together tightly by means of theset screws and the non-magnetic metallic plates C are properly held onthe surface of the magnet and soft iron pieces in such a way as tobridge over the contacting lines of the pieces by means of the springarm H.

When the necessary prearrangements are completed, one end of thecovering plates on both sides is spot-welded to one of the soft ironpieces at the points marked D. Then the covering plates are heated by'agas burner, for e ample, for a few seconds, and the other end of thecovering plates while still hot are spot-welded to the other soft ironpiece at the points marked D.

In the illustrated instance in Figs. 3 and 4 the magnet A and thenon-magnetic metallic plates C are not welded together, because the softiron pieces hold the magnet so tightly due to the contraction of theplates that the welding becomes unnecessary, but the direct welding tothe magnet may be used wherever such method is deemed desirable,depending upon the sizes and shapes of the built-up magnet.

.Ihe built-up permanent magnet manufactured by this new process containsno screws, neither is it riveted nor soldered. This is anew product as abuilt-up permanent maanet' per se.

What I claim is: a I

1. A manutacturinz process of a built-u permanent maanet wherein a sortiron piece is attached in facial contact to opposite poles or apermanent magnet piece, and non-magnetic plates are placed to coveropposite sides of said permanent magnet and soft iron pieces, and saidplates are spot welded to one o! the pieces at one side or a racialcontact and heated and while hot, welded to another c5 said pieces atthe opposite of said facial contact so that tlaht facial conattalned bythe contraction of the metal AA in s lat-se a,sos,sos

2. A manufacturing process oi a permanent ma net wherein two soit ironpieces are attached in facial contact to a permanent magnet piece atopposite poles, the faces of contact beinl approximately parallel.non-nuanetic plates are placed on opposite sides of said permanentmagnet and soft iron pieces and said plates are spot welded to one ofsaid soft iron Pieces and heated and while hot, spot welded tothe otherof said soft iron pieces so that the permanent maa'net piece is firmlyheld between the soft iron pieces on contraction of the metal plates.

TAKESHI ISEKI.

